Overheat protection method and cooling device for multi-turn coil

Abstract

The present invention belongs to the technical field of metal heat treatment, and provides an overheating protection method for a multi-turn coil and a cooling device thereof. Before the start of induction heating, the quality and residual amount of the coolant are automatically judged, and replenishment or replacement operations are performed as needed. The flow rate and inlet and outlet channels of the coolant can be dynamically adjusted according to the temperature change of the coil. The cooling device includes a cooling supply component, a slide component, an infrared thermometer, a power supply and a controller. A plurality of coolant channels are arranged on the coil, and the coolant channels are respectively connected to the liquid supply pipe and the liquid return pipe through solenoid valves. The infrared thermometer is arranged on the slide component, and a loop liquid path, a turbidity sensor and a liquid level meter are arranged in the cooling supply component. The controller is connected to the cooling supply component, the slide component and the infrared thermometer through electrical signals. The device can realize closed-loop control between induction heating and coolant circulation state according to the change of coil temperature, thereby effectively improving the heat dissipation efficiency of the coil.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal heat treatment, and in particular relates to an overheat protection method for a multi-turn coil and a cooling device thereof. Background Art

[0002] A coil is an inductive component made of a material with excellent electrical conductivity. It consists of one or more conductive coils with specific electromagnetic properties. By winding a wire into a spiral or other shape, an alternating current flows through it, generating a magnetic field of the same frequency around the coil. This magnetic field can be used to achieve electromagnetic heating, induce voltage, and store energy, resulting in widespread use in various electrical and electronic devices. However, during operation, the coil temperature rises due to resistive heating and heat conduction from other components. This not only reduces the efficiency and performance of the device but can also cause insulation degradation, leading to the risk of short circuits or insulation failure, seriously impacting the safety and service life of the device. Therefore, coils are typically equipped with cooling measures to prevent overheating and ensure efficient operation. In electromagnetic heating applications, when a workpiece is placed in the coil's magnetic field, eddy currents are generated within it. These eddy currents generate Joule heating within the workpiece, causing it to rapidly heat up. During this process, the electromagnetic coupling between the coil and the workpiece determines the number and density of magnetic field lines entering the workpiece, a key factor affecting heating efficiency and accuracy. However, as the workpiece temperature rises, the coil also heats up due to its own resistive heating and absorption of radiant heat from the workpiece. Rising temperature affects coils in many ways. First, as coil temperature rises, the resistance of the conductive material increases, weakening the magnetic field generated by the coil, thereby reducing heating efficiency and electromagnetic coupling with the workpiece. Second, rising temperature causes thermal expansion of the material, inducing mechanical stress changes in the coil, leading to geometric deformation of the coil. This deformation changes the physical distance between the coil and the workpiece, and this distance change significantly affects electromagnetic coupling efficiency. Especially in high-frequency electromagnetic heating, even slight changes in distance can lead to fluctuations in power density, affecting heating uniformity and accuracy. Furthermore, if the coil is made of ferromagnetic material, rising temperature can also reduce the coil's magnetic permeability, and even cause it to lose its magnetism above the Curie point, resulting in a significant imbalance in the magnetic field distribution, which directly affects the induction heating effect. Therefore, employing effective heat dissipation and cooling technologies to control coil temperature is not only a key factor in ensuring the proper operation of the entire induction heating system, but also a vital guarantee for ensuring heating accuracy and quality, and promoting high-end precision manufacturing.

[0003] Patent CN101162636B discloses a coil protective layer for a medium-frequency furnace. The protective layer is composed of high-temperature resistant hollow balls, powder materials and binders. After being coated on the surface of the coil, it plays a heat-insulating role. However, the protective layer cannot completely block heat transfer. When the cooling effect of the coolant decreases or when heated for a long time, the temperature of the coil will continue to rise or even overheat. Patent CN214039528U discloses a coil protection device for a medium-frequency induction heating furnace, which can realize automatic replenishment of coolant. However, after heating starts, the coil temperature is also directly affected by the heating time, heating temperature, etc., and closed-loop control between induction heating and coolant circulation status is achieved according to the change in coil temperature. It can not only control the change in coil temperature, but also is an effective way to match appropriate cooling hydraulics and reduce resource waste. However, this device cannot effectively prevent the coil from overheating in essence. Therefore, it is necessary to design an overheating protection method and cooling device for multi-turn coils. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides an overheating protection method and a cooling device for a multi-turn coil. Through an effective heat dissipation and cooling structure, combined with a system for dynamically monitoring the status of the coolant, a coil temperature control and management mechanism is established to prevent the coil from overheating due to prolonged heating, mismatch between the coil and the workpiece, and insufficient cooling hydraulic pressure. It also effectively prevents the deterioration of the coolant quality due to industrial dust and metal corrosion, ensuring that the coil operates continuously and stably within a safe temperature range, thereby extending the life of the equipment and improving the reliability of the cooling device.

[0005] The present invention provides an overheat protection method for a multi-turn coil, which comprises the following steps:

[0006] S1. Determine the upper limit turbidity N of the coolant according to process requirements max , determine the length L of the heated workpiece and set the first warning temperature T max1 , Second warning temperature T max2 and the third warning temperature T max3 , determine the upper limit of the liquid level H max , real-time measurement of turbidity N;

[0007] S2. Determine N≥N max Is it true? If so, go to step S3; otherwise, go to step S4;

[0008] S3, open the first solenoid valve, when the liquid level measured by the level gauge H w =0, close the first solenoid valve and open the second solenoid valve until H w =H max When N<N max When the first solenoid valve and the second solenoid valve are closed, step S5 is executed;

[0009] S4, turn off the turbidity sensor and judge H w <H max Is it true? If H w <H max Then open the second solenoid valve until H w =H max When the second solenoid valve is closed, step S5 is executed; if H w >H max Then directly execute step S5;

[0010] S5. Select the coolant interface Y according to the axial length L of the heated workpiece m , start the motor to move the infrared thermometer to the coolant interface Y m Department;

[0011] S6, open the coolant interface Y1 and the coolant interface Y m , the coolant is delivered to the coolant interface Y1 through the liquid pump and the coolant is m outflow;

[0012] S7, determine the coolant real-time flow Q ≥ coolant flow lower limit Q min Is it true? If so, start the power supply and execute step S8. Otherwise, check whether the cooling device is working properly and re-judge the coolant real-time flow rate Q≥ the coolant flow lower limit Q. min Is it established, until it is established and execute step S8;

[0013] S8, real-time monitoring of coolant interface Y m Temperature T Ym , according to T Ym Select the coolant inlet and outlet ports and determine T Ym ≥T max3 If so, turn off the power supply, check if the cooling device is working properly, and then return to step S7. Otherwise, determine whether T max2 <T Ym <T max3 Is it established? If so, execute step S81 according to the coolant interface number m. Otherwise, determine T max1 <T Ym <T max2 Is it true? If so, the solenoid valve R m Switch to liquid inlet state, coolant interface Y m Switch to the liquid inlet and execute step S82 according to the coolant interface number m. If not, directly execute step S9;

[0014] S9, turn on the power and determine whether the heated workpiece meets the heat treatment requirements. If so, execute step S10; otherwise, return to step S7;

[0015] S10, turn off the power, remove the heated workpiece, and determine T Ym <T max1 Is it true? If so, close the liquid pump and all solenoid valves. Otherwise, keep the current solenoid valve open and closed and continue cooling until T Ym <T max1 , induction heating ends.

[0016] Preferably, step S81 is: if m=2, increase the real-time flow rate Q of the coolant and execute step S9; if m>2, the odd-numbered solenoid valves are all switched to the liquid inlet state, and the corresponding coolant interfaces are switched to the liquid inlet; the even-numbered solenoid valves are all switched to the liquid outlet state, and the corresponding cooling interfaces are switched to the liquid outlet, and execute step S9.

[0017] Preferably, step S82 is: if m=2, solenoid valves R3~R n All are switched to the liquid outlet state, coolant interface Y3~Y n Switch to the liquid outlet, execute step S9, if m>2, solenoid valve R2~R m-1 All are switched to the liquid outlet state, coolant interface Y2~Y m-1 Switch to the liquid outlet and execute step S9.

[0018] In the second aspect, the present invention also provides a cooling device for multi-turn coils, which includes a slide assembly, an infrared thermometer, a controller, a liquid pump, a cooling supply assembly, a solenoid valve and a power supply. The cooling supply assembly includes a liquid tank, a toroidal partition, a turbidity sensor, a liquid level meter, a flow meter, a first solenoid valve and a second solenoid valve. The toroidal partition is arranged in the liquid tank to form a toroidal liquid path. The first end of the toroidal liquid path is provided with a coil liquid inlet and a liquid tank discharge port, and the second end of the toroidal liquid path is provided with a coil liquid return port and a liquid tank liquid inlet. The liquid level meter and turbidity sensor are arranged at the coil liquid inlet, the flow meter is connected to the coil liquid inlet channel, the first solenoid valve is connected to the liquid tank discharge port, and the second solenoid valve is connected to the liquid tank inlet.

[0019] Preferably, the coil is provided with a plurality of coolant interfaces, each of which is provided with the solenoid valve, and the distance D between adjacent coolant interfaces is less than D max The coolant interface is connected to the coil liquid inlet channel and the coil liquid return channel through the solenoid valve respectively.

[0020] Preferably, the slide assembly includes a temperature measuring bracket, a motor, a screw, a distance measuring bracket and a distance measuring sensor, the infrared thermometer is arranged on the temperature measuring bracket, the distance measuring sensor is arranged on the distance measuring bracket, and the controller is connected to the motor, distance measuring sensor, infrared thermometer, liquid pump, first solenoid valve, second solenoid valve, turbidity sensor, liquid level meter, flow meter, solenoid valve and power supply through electrical signals respectively.

[0021] Preferably, the first solenoid valve and the second solenoid valve in the cooling supply assembly are both two-position two-way valves, the liquid circuit is closed when the valve core is in the middle position, and the liquid circuit is opened when the valve core is in motion.

[0022] Preferably, the solenoid valve is a three-position three-way valve, and the liquid circuit is closed when the valve core is in the middle position.

[0023] Preferably, the distance D between adjacent coolant interfaces is smaller than the maximum distance D max , and the maximum distance D max The determination method is: establish the influence equation of the length L of the heated workpiece on the temperature T2 at the coil outlet, set the maximum value of the temperature T2 at the coil outlet to obtain D max , the influence equation of T2 and L is:

[0024] ;

[0025] Where T1 is the maximum heating temperature of the heated workpiece, T0 is the temperature at the coil entrance, σ is the Stefan-Boltzmann constant, ε is the surface emissivity, and A ... s is the surface area of ​​the coil, ρ is the density of the coolant, c p is the specific heat capacity of the coolant, Q min This is the lower limit of coolant flow.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention provides an overheat protection method for multi-turn coils. By monitoring the coolant, it effectively prevents the accumulation of impurities caused by prolonged coolant use, thus avoiding reduced cooling efficiency. A built-in liquid level gauge accurately monitors the liquid level, preventing coil overheating or excessive overflow caused by insufficient coolant, thereby ensuring safe equipment operation. A circular baffle is installed within the liquid tank, with the coil's liquid inlet and return port located at either end of the baffle. This allows coolant flowing back from the coil to fully dissipate heat within the baffle before recirculating into the coil, effectively improving the coolant's cooling efficiency.

[0028] 2. This invention is used in a cooling device for multi-turn coils. Multiple coolant channels are provided on the coils, equipped with real-time temperature monitoring. When the channel temperature reaches a preset alarm threshold, the corresponding solenoid valve automatically switches, adjusting the flow rate and opening and closing status of different coolant channels based on the temperature rise. This automatically adjusts the coolant flow rate and circulation pattern based on coil temperature changes, effectively enhancing heat dissipation.

[0029] 3. This invention is used in a cooling device for multi-turn coils. Through a controller, it achieves fully integrated control of liquid level, liquid quality, temperature, and other signals with the solenoid valve, motor, power supply, and liquid pump. This effectively reduces manual operation errors and labor costs, and improves the automation level and reliability of the coil cooling device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Flowchart of the overheat protection method for a multi-turn coil according to the present invention;

[0031] Figure 2 Schematic diagram of the cooling device for multi-turn coils according to the present invention;

[0032] Figure 3 A top view of a cooling device for a multi-turn coil according to the present invention;

[0033] Figure 4 It is a side view of the cooling device for multi-turn coils of the present invention.

[0034] Main reference numerals:

[0035] 1-slide assembly, 11-temperature measuring bracket, 12-motor, 13-screw, 14-distance measuring bracket, 15-distance measuring sensor, 2-infrared thermometer, 3-controller, 4-liquid pump, 5-cooling supply assembly, 51-liquid tank, 52-liquid tank inlet, 53-first solenoid valve, 54-liquid tank drain port, 55-coil liquid inlet, 56-second solenoid valve, 57-reciprocating partition, 58-turbidity sensor, 59-liquid level meter, 510-coil return liquid port, 511-coil liquid inlet channel, 512-coil return liquid channel, 513-flow meter, 6-solenoid valve, 7-coil, 71-cooling liquid interface, 9-power supply. DETAILED DESCRIPTION

[0036] To fully describe the technical content, structural features, objectives and effects of the present invention, the following is a detailed description with reference to the accompanying drawings.

[0037] like Figure 1 As shown, the overheat protection method for a multi-turn coil provided by the present invention comprises the following steps:

[0038] S1. Determine the upper limit turbidity N of the coolant according to process requirements max, determine the length L of the heated workpiece and set the first warning temperature T max1 , Second warning temperature T max2 and the third warning temperature T max3 , determine the upper limit of the liquid level H max , real-time measurement of turbidity N.

[0039] S2. Determine N≥N max If yes, go to step S3; otherwise, go to step S4.

[0040] S3, open the first electromagnetic valve 53, when the liquid level measured by the liquid level meter 59 is H w =0, close the first solenoid valve 53 and open the second solenoid valve 56 until H w =H max When N<N max When , the first solenoid valve 53 and the second solenoid valve 56 are closed, and step S5 is executed.

[0041] S4, turn off the turbidity sensor 58, and judge H w <H max Is it true? If H w <H max Then open the second solenoid valve 56 until H w =H max When the second solenoid valve 56 is closed, step S5 is executed; if H w >H max Then directly execute step S5.

[0042] S5. Select the coolant interface Y according to the axial length L of the heated workpiece m , start the motor 12 to move the infrared thermometer 2 to the coolant interface Y m Place.

[0043] S6, open the coolant interface Y1 and the coolant interface Y m , the coolant is delivered to the coolant interface Y1 through the liquid pump 4 and the coolant is m outflow.

[0044] S7, determine the coolant real-time flow Q ≥ coolant flow lower limit Q min Is it established? If so, start the power supply 9 and execute step S8. Otherwise, check whether the cooling device is working properly and then re-judge the coolant real-time flow rate Q≥ the coolant flow lower limit Q. min If it is established, execute step S8.

[0045] S8, real-time monitoring of coolant interface Y m Temperature T Ym , according to T YmSelect the coolant inlet and outlet ports and determine T Ym ≥T max3 If so, turn off the power supply, check if the cooling device is working properly, and then return to step S7. Otherwise, determine whether T max2 <T Ym <T max3 Is it established? If so, execute step S81 according to the coolant interface number m. Otherwise, determine T max1 <T Ym <T max2 Is it true? If so, the solenoid valve R m Switch to liquid inlet state, coolant interface Y m Switch to the liquid inlet and execute step S82 according to the coolant interface number m; if not, directly execute step S9.

[0046] Step S81 is: if m=2, increase the real-time coolant flow Q and execute step S9; if m>2, the odd-numbered solenoid valves are all switched to the liquid inlet state, and the corresponding coolant interfaces are switched to the liquid inlet; the even-numbered solenoid valves are all switched to the liquid outlet state, and the corresponding cooling interfaces are switched to the liquid outlet, and execute step S9.

[0047] Step S82 is: if m=2, solenoid valves R3~R n All are switched to the liquid outlet state, coolant interface Y3~Y n Switch to the liquid outlet, execute step S9, if m>2, solenoid valve R2~R m-1 All are switched to the liquid outlet state, coolant interface Y2~Y m-1 Switch to the liquid outlet and execute step S9.

[0048] S9, turn on the power supply 9, and determine whether the heated workpiece meets the heat treatment requirements. If so, execute step S10, otherwise return to execute step S7.

[0049] S10, turn off the power supply 9, remove the heated workpiece, and determine T Ym <T max1 Is it established? If so, close the liquid pump 4 and all electromagnetic valves 6. Otherwise, keep the current open and closed state of the electromagnetic valve 6 and continue cooling until T Ym <T max1 , induction heating ends.

[0050] like Figures 2 to 4As shown, a cooling device for a multi-turn coil includes a slide assembly 1, an infrared thermometer 2, a controller 3, a liquid pump 4, a cooling supply assembly 5, a solenoid valve 6, a coil 7 and a power supply 9. The cooling supply assembly 5 includes a liquid tank 51, a meandering partition 57, a turbidity sensor 58, a liquid level meter 59, a flow meter 513, a first solenoid valve 53 and a second solenoid valve 56. The temperature of the coolant rises after flowing through the coil 7. A meandering partition 57 is provided in the liquid tank 51 to form a meandering liquid path. A wire is provided at the first end of the meandering liquid path. The coil liquid inlet 55 and the liquid tank discharge port 54 are provided at the second end of the looped liquid path. The coil liquid return port 510 and the liquid tank liquid inlet 52 are provided. The liquid level meter 59 and the turbidity sensor 58 are arranged at the coil liquid inlet 55. The liquid level meter 59 controls the amount of coolant. The turbidity sensor 58 detects the turbidity of the coolant. The flow meter 513 is connected to the coil liquid inlet channel 511. The first solenoid valve 53 is connected to the liquid tank discharge port 54. The first solenoid valve 53 controls the discharge of coolant. The second solenoid valve 56 is connected to the liquid tank liquid inlet 52. The slide assembly 1 includes a temperature measuring bracket 11, a motor 12, a screw 13, a distance measuring bracket 14 and a distance measuring sensor 15. The infrared thermometer 2 is arranged on the temperature measuring bracket 11, and the distance measuring sensor 15 is arranged on the distance measuring bracket 14. The controller 3 is connected to the motor 12, the distance measuring sensor 15, the infrared thermometer 2, the liquid pump 4, the first solenoid valve 53, the second solenoid valve 56, the turbidity sensor 58, the liquid level meter 59, the flow meter 513, the solenoid valve 6, and the power supply 9 through electrical signals. The first solenoid valve 53 and the second solenoid valve 56 in the cooling supply assembly 5 are both two-position two-way valves. When the valve core is in the middle position, the liquid circuit is closed, and when the valve core is actuated, the liquid circuit is opened. The solenoid valve 6 is a three-position three-way valve. When the valve core is in the middle position, the liquid circuit is closed. A plurality of coolant interfaces 71 are provided on the coil 7, and the coolant interfaces 71 are numbered in sequence as [Y1, Y2,…, Y m ,…,Y n ], the cooling liquid interface 71 is provided with a solenoid valve 6, and the solenoid valves 6 are numbered in sequence as [R1, R2, ..., R m ,…,R n ], the distance D between adjacent coolant interfaces 71 is less than D max The coolant interface 71 is connected to the coil liquid inlet channel 511 and the coil liquid return channel 512 through the solenoid valve 6, respectively, to realize automatic monitoring and judgment of the coolant remaining amount and liquid quality, and automatically replace the coolant. During induction heating, the circulation state of the coolant is adjusted in real time according to the change of the coil 7 temperature to ensure the cooling effect of the coil 7.

[0051] The following is a further description of the overheat protection method and cooling device for a multi-turn coil of the present invention in conjunction with the embodiments:

[0052] To ensure the cooling rate, limit T2 ≤ the first warning temperature T max1 In this embodiment, T max1=60℃, T1=1500℃, T0=25℃, A s =1m 2 ,σ=5.67×10−8W / (m 2 ·K 4 ), surface emissivity ε = 0.1, coolant density ρ = 1000 kg / m 3 , the specific heat capacity of the coolant c p =4184 J / (kg·K), coolant flow rate Q=0.01 m 3 / s is substituted into the formula to obtain the maximum value D of the distance D between two adjacent coolant interfaces 71 along the winding direction of the coil 7. max ≤3.29m.

[0053] After the coolant interface 71 is determined, a solenoid valve 6 is set at each coolant interface 71. The solenoid valves 6 are numbered in sequence as [R1, R2, ..., R m ,…,R n ];like Figure 3 As shown, each solenoid valve 6 is connected to the first end of the coil liquid inlet channel 511 and the first end of the coil liquid return channel 512. The second end of the coil liquid inlet channel 511 is connected to the liquid pump, and the second end of the coil liquid return channel 512 is connected to the coil liquid return port 510. During induction heating, the coolant circulation state will be dynamically adjusted according to the temperature changes of the coil 7. Therefore, the solenoid valves 6 installed at the coolant interface 71 are all three-way valves with three positions. When the valve core is in the neutral position, the liquid circuit is closed. When the valve core is actuated, the corresponding coolant interface 71 switches to a liquid inlet or a liquid outlet.

[0054] The present invention is used for an overheating protection method and cooling device for a multi-turn coil. The method adopts an effective heat dissipation and cooling structure, combined with a system for dynamically monitoring the status of the coolant, to establish a coil temperature control and management mechanism to prevent the coil from overheating due to prolonged heating, mismatch between the coil and the workpiece, and insufficient cooling hydraulic pressure. The method also effectively prevents the coolant quality from deteriorating due to industrial dust and metal corrosion, ensuring that the coil 7 operates continuously and stably within a safe temperature range, thereby extending the life of the equipment and improving the reliability of the cooling system.

[0055] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for overheat protection of a multi-turn coil, characterized in that: It includes the following steps: S1. Determine the upper limit turbidity N of the coolant according to process requirements max , determine the length L of the heated workpiece and set the first warning temperature T max1 , Second warning temperature T max2 and the third warning temperature T max3 , determine the upper limit of the liquid level H max , real-time measurement of turbidity N; S2. Determine N≥N max Is it true? If so, go to step S3; otherwise, go to step S4; S3, open the first solenoid valve, when the liquid level measured by the level gauge H w =0, close the first solenoid valve and open the second solenoid valve until H w =H max When N<N max When the first solenoid valve and the second solenoid valve are closed, step S5 is executed; S4, turn off the turbidity sensor and judge H w <H max Is it true? If H w <H max Then open the second solenoid valve until H w =H max When the second solenoid valve is closed, step S5 is executed; if H w >H max Then directly execute step S5; S5. Select the coolant interface Y according to the axial length L of the heated workpiece m , start the motor to move the infrared thermometer to the coolant interface Y m Department; S6, open the coolant interface Y1 and the coolant interface Y m , the coolant is delivered to the coolant interface Y1 through the liquid pump and the coolant is m outflow; S7, determine the coolant real-time flow Q ≥ coolant flow lower limit Q min Is it true? If so, start the power supply and execute step S8. Otherwise, check whether the cooling device is working properly and re-judge the coolant real-time flow rate Q≥ the coolant flow lower limit Q. min Is it established, until it is established and execute step S8; S8, real-time monitoring of coolant interface Y m Temperature T Ym , according to T Ym Select the coolant inlet and outlet ports and determine T Ym ≥T max3 If so, turn off the power supply, check if the cooling device is working properly, and then return to step S7. Otherwise, determine whether T max2 <T Ym <T max3 Is it established? If so, execute step S81 according to the coolant interface number m. Otherwise, determine T max1 <T Ym <T max2 Is it true? If so, the solenoid valve R m Switch to liquid inlet state, coolant interface Y m Switch to the liquid inlet and execute step S82 according to the coolant interface number m. If not, directly execute step S9; Step S81 is: if m=2, increase the real-time coolant flow rate Q and execute step S9; if m>2, all odd-numbered solenoid valves are switched to the liquid inlet state, and the corresponding coolant interfaces are switched to the liquid inlet; all even-numbered solenoid valves are switched to the liquid outlet state, and the corresponding cooling interfaces are switched to the liquid outlet, and execute step S9; Step S82 is: if m=2, solenoid valves R3~R n All are switched to the liquid outlet state, coolant interface Y3~Y n Switch to the liquid outlet, execute step S9, if m>2, solenoid valve R2~R m-1 All are switched to the liquid outlet state, coolant interface Y2~Y m-1 Switch to the liquid outlet and execute step S9; S9, turn on the power and determine whether the heated workpiece meets the heat treatment requirements. If so, execute step S10, otherwise return to step S7; S10, turn off the power, remove the heated workpiece, and determine T Ym <T max1 Is it true? If so, close the liquid pump and all solenoid valves. Otherwise, keep the current solenoid valve open and closed and continue cooling until T Ym <T max1 , induction heating ends.

2. A cooling device for the overheat protection method of a multi-turn coil according to claim 1, characterized in that: It includes a slide assembly, an infrared thermometer, a controller, a liquid pump, a cooling supply assembly, a solenoid valve and a power supply. The cooling supply assembly includes a liquid tank, a toroidal partition, a turbidity sensor, a liquid level meter, a flow meter, a first solenoid valve and a second solenoid valve. The toroidal partition is arranged in the liquid tank to form a toroidal liquid path. The first end of the toroidal liquid path is provided with a coil liquid inlet and a liquid tank discharge port, the second end of the toroidal liquid path is provided with a coil liquid return port and a liquid tank liquid inlet, the liquid level meter and the turbidity sensor are arranged at the coil liquid inlet, the flow meter is connected to the coil liquid inlet channel, the first solenoid valve is connected to the liquid tank discharge port, and the second solenoid valve is connected to the liquid tank liquid inlet.

3. The cooling device for a multi-turn coil according to claim 2, characterized in that: The slide assembly includes a temperature measuring bracket, a motor, a screw, a distance measuring bracket and a distance measuring sensor. The infrared thermometer is arranged on the temperature measuring bracket, and the distance measuring sensor is placed on the distance measuring bracket. The controller is connected to the motor, distance measuring sensor, infrared thermometer, liquid pump, first solenoid valve, second solenoid valve, turbidity sensor, liquid level meter, flow meter, solenoid valve and power supply through electrical signals.

4. The cooling device for a multi-turn coil according to claim 2, characterized in that: The coil is provided with a plurality of coolant interfaces, each of which is provided with the solenoid valve. The coolant interfaces are respectively connected to the coil liquid inlet channel and the coil liquid return channel through the solenoid valve.

5. The cooling device for a multi-turn coil according to claim 2, characterized in that: The first solenoid valve and the second solenoid valve in the cooling supply assembly are both two-position two-way valves. When the valve core is in the middle position, the liquid circuit is closed, and when the valve core is in motion, the liquid circuit is opened.

6. The cooling device for a multi-turn coil according to claim 2, characterized in that: The solenoid valve is a three-position, three-way valve, and the liquid circuit is closed when the valve core is in the middle position.

7. The cooling device for a multi-turn coil according to claim 4, characterized in that: The distance D between adjacent coolant interfaces is less than the maximum distance D max , and the maximum distance D max The determination method is: establish the influence equation of the length L of the heated workpiece on the temperature T2 at the coil outlet, set the maximum value of the temperature T2 at the coil outlet to obtain D max , the influence equation of T2 and L is: ； Where T1 is the maximum heating temperature of the heated workpiece, T0 is the temperature at the coil entrance, σ is the Stefan-Boltzmann constant, ε is the surface emissivity, and A ... s is the surface area of ​​the coil, ρ is the density of the coolant, c p is the specific heat capacity of the coolant, Q min This is the lower limit of coolant flow.

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